Method for repairing a connecting device for the electrical connection and for supplying and carrying away the coolant to and from the hollow conductor elements of the stator winding bars of electrical machines

ABSTRACT

A method of repairing a joint between conductor elements of a stator winding bar of an electrical machine and a connecting device connected to an end of the stator winding bar for providing electrical connection and coolant flow for the conductor elements includes the steps of removing an existing connecting device from the end of the stator winding bar; aligning the conductors of the end of the stator winding bar by heating the bar end to above the flow point of the braze holding the conductors in position while simultaneously holding the conductors of the end of the stator winding bar under compression in two orthogonal directions perpendicular to the length of the stator winding bar; forming slots in the end of the stator winding bar and at locations such that the slots extend to locations where the conductor elements abut one another; applying an electrically conductive first connecting part onto the end of the stator winding bar such that the first connecting part substantially surrounds the end of the stator winding bar and sealing the gaps and slots.

This is a continuation-in-part of application Ser. No. 08/415,362, filedApr. 3, 1995, now U.S. Pat. No. 5,557,837.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method for repairing or replacing aconnecting device for electrical connection and for supplying andcarrying away the coolant to and from the hollow conductor elements ofthe stator winding bars of electrical machines, in the case of whichconnecting device the hollow conductor elements and, if appropriate inthe case of a stator winding which also comprises solid conductorelements as well as hollow conductor elements, all the conductorelements are surrounded by a metallic component and are brazed theretoand to one another, which component overhangs the conductor elementsforming a water chamber and ends in a connecting fitting for coolantsupply and carrying the coolant away.

2. Discussion of Background

In the stator winding overhang of water-cooled electrical machines, thecoolant is supplied from annular header lines via insulating hoses tothe so-called water chambers at the end of the conductor bars. The waterchamber is formed by a connecting device in which the hollow conductorelements are surrounded by a metallic component and are brazed orsoldered thereto and to one another. The metallic component overhangsthe conductor elements to form this water chamber. It ends in aconnecting fitting for coolant supply and carrying coolant away. Theconnecting device is at the same time also used as the electricalconnection.

The connecting device is subject to high mechanical loads (vibration)during operation. Even very small leakages lead to consequential damageto the electrical machine. If such damage occurs, the brazed or solderedjoints--if at all possible--must be replaced. In general, only theremoval or even the complete replacement of the stator winding remains.There is thus a major requirement for a repair method which can becarried out without removal of the stator winding.

SUMMARY OF THE INVENTION

Accordingly, one object of the invention is to provide a novel methodfor repairing a connecting device of the generic type mentionedinitially, which method can be carried out easily and manages withoutremoval or even replacement of the stator winding, but at the same timemakes possible leakage-free brazed or soldered joints.

This object is achieved according to the invention by a repair methodwhich comprises removal of the existing connecting device from the barend by inductive heating; cleaning the bar end in the region where thenew connecting device is intended to be mounted; aligning the conductorsof the end of the stator winding bar by heating the bar end to above theflow point of the braze holding the conductors in position whilesimultaneously holding the conductors of the end of the stator windingbar under compression in the two orthogonal directions perpendicular tothe length of the stator winding bar; material-cutting machining of theend surface of the bar end, especially by milling; introducing narrowslots between adjacent conductor elements into the end of the bar in thetransverse direction and vertical direction; pushing on a firstconnecting part which completely surrounds the bar end; fillingremaining gaps between the first connecting part and the outer surfacesof the bar end with copper foil and/or braze foil; filling the narrowslots, which have been introduced into the end of the bar, with copperfoil and/or braze foil; inductive heating of the first connecting partand of the bar end and brazing with the addition of braze; at leastvisual inspection of the braze joint thus created; fitting a secondconnecting part to the free end surface of the first connecting part bybrazing; and testing the sealing of the connecting device created inthis way.

This object is also achieved according to the invention by a repairmethod which comprises at the steps of removing an existing connectingdevice from the end of the stator winding bar; aligning the conductorsof the end of the stator winding bar by heating the bar end to above theflow point of the braze holding the conductors in position whilesimultaneously holding the conductors of the end of the stator windingbar under compression in two orthogonal directions perpendicular to thelength of the stator winding bar; applying an electrically conductivefirst connecting part onto the end of the stator winding bar such thatsaid first connecting part substantially surrounds said end of thestator winding bar; and sealing any gaps between the end of the statorwinding bar and said electrically conductive first connecting part.

The invention is in this case based on the idea of managing with aminimum of modifications to the existing connecting device and at thesame time retaining inspection of the quality of the repair measures atany time. This includes, inter alia, the deliberate creation of clean,defined, comparatively large-area braze points and the capability tofill the resulting gaps with filling strips made of copper and braze, ora combination of beth, such that only extremely small gaps still remainwhich are later filled without any residue during brazing, as a resultof the capillary effect. Furthermore, the splitting of the connectingdevice in two is to be emphasized, which allows accessibility, and thusthe capability to inspect the braze joints to be created, at any time.This splitting in two furthermore makes possible great flexibility inthe design of the two connecting parts, particularly with respect totheir separating surfaces, as well. The latter can be designed suchthat, on the one hand, the brazing/testing of the first connecting partcan be carried out easily whereas, on the other hand, the secondconnecting part makes possible the connection to the existing coolantlines as well as to the electrical connections virtually "seamlessly".

While the description refers to braze or brazing, it may be appreciatedthat the invention also encompasses the use of solder and soldering, andso the term "braze" or "brazing" as used in the remainder of thisspecification should be interpreted to optionally include solder orsoldering.

Exemplary embodiments of the invention and further advantages which canbe achieved thereby are explained in more detail in the following text,with reference to the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 shows a longitudinal section through a known connecting devicefor the electrical connection and for supplying and carrying away thecoolant to and from the hollow conductor elements of the stator windingbars of electrical machines;

FIG. 2 shows a cross section through the connecting device according toFIG. 1, along the line AA in said figure;

FIG. 3 shows a cross section through the bar end close to the endsurface after the introduction of slots between adjacent conductorelements;

FIG. 4 shows a longitudinal section through the bar end according toFIG. 3;

FIG. 5 shows a longitudinal section through a connecting device as isused for the repair method according to the invention, slots which havebeen introduced into the end surface of the conductor bar being filledwith special filling pieces;

FIG. 6 shows the detail X from FIG. 5 on an enlarged scale;

FIG. 7 shows a longitudinal section through a connecting device as isused for the repair method according to the invention, the hollowconductor ends subsequently having been widened, as a modification toFIGS. 5 and 6;

FIG. 8 shows a longitudinal section through the bar end of FIG. 7 closeto the end surface, after the introduction of holes at the meeting pointof four hollow conductors, and subsequent filling of these holes withcopper round material;

FIG. 9 shows a cross section through the bar end according to FIG. 8,along the line BB in said figure;

FIG. 10 shows a longitudinal section through a connecting device inwhich the separating surface between the two connecting parts is laid inthe direction of the connecting fitting;

FIG. 11 shows a cross section through the bar end of a stator windingbar which also contains solid conductor elements, as well as hollowconductor elements;

FIGS. 12A and 12B are respectively sectional and side viewsschematically showing the brazing of the first connecting part to theend of the stator winding bar using a hydraulic pressing tool and aninduction heating coil; and

FIG. 13 is a schematic orthogonal view of an embodiment in which thefirst connecting part has a window and a floating window cover plate formaintaining the aligned position of the conductor ends during thebrazing of the first connecting part onto the bar end.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, theobject used as the basis for the repair method which is to be describedin the following text is a known connecting device for the electricalconnection and for supplying and carrying away the coolant from thehollow conductors of the stator winding bars of an electrical machine,as is illustrated schematically in FIGS. 1 and 2.

The stator winding bar which, in the case of the example is constructedonly from hollow conductor elements 1, is provided at its end with aconnecting device in the form of a metallic component 2. The lattersurrounds the totality of all the conductor elements 1, overhangs themexternally to form a water chamber 3 into which the cooling channels 4open into the conductor elements 1, and ends in a connecting fitting 5for coolant supply and carrying the coolant away.

The conductor elements 1 are silver-brazed to one another and to themetallic component. The braze gaps, which are illustrated excessivelylarge in FIG. 1 and FIG. 2 and are filled with braze are designated by6. The electrical connection S (indicated by dashed lines in FIG. 1) ofthe connecting device is located in the case of the example on theoutside of the water chamber 3, and has been omitted in FIG. 1 becauseit is not necessary for understanding of the invention.

After the machines have been operated for a time, leakages can occur atthe braze joints. The wall of the water chamber 3 itself can also becomeunsound if--as is normal in a large number of relatively oldmachines--it is made of cast copper. The consequence is that coolingwater passes into the winding overhang space or--as is far moredangerous--into the conductor bar, which must be avoided under allcircumstances. Because of the confined spatial conditions in the windingoverhang space, the replacement of such connecting devices is extremelytiresome. As a rule, removal of the stator winding is not possible, foreconomic reasons. The invention now comes into play here.

The repair method according to the invention is presented in summaryform as follows, and comprises essentially the following method steps:

a) removal of the existing connecting device (metallic component 2) fromthe bar end by inductive heating;

b) cleaning the bar end in the region where the new connecting device isintended to be mounted;

c) aligning the conductors of the end of the stator winding bar byheating the bar end to above the flow point of the braze holding theconductors in position while simultaneously holding the conductors ofthe end of the stator winding bar under compression in the twoorthogonal directions perpendicular to the length of the stator windingbar;

d) material-cutting machining of the end surface of the bar end,especially by milling;

e) introducing narrow slots 7 between adjacent conductor elements 1 intothe end of the bar in the transverse direction and vertical direction inorder to remove "old" braze between the conductor elements down to apredefined depth;

f) pushing on a first connecting part 2a which is made of copper andcompletely surrounds the bar end;

g) filling remaining gaps between the first connecting part 2a and theouter surfaces of the bar end with copper foil and/or braze foil;

h) filling the narrow slots 7, which have been introduced into the endof the bar, with copper foil and/or braze foil or a combination of both;

i) inductive heating of the first connecting part 2a and of the bar endand brazing with the addition of braze;

j) at least visual inspection of the braze joint thus created;

k) fitting a second connecting part 2b made of copper to the free endsurface of the first connecting part 2a by brazing;

l) testing the sealing of the connecting device created in this way.

In step a, the metallic component 2 is heated by inductive means to themelting temperature of the braze and is pulled off the bar end. Devicesfor deliberate local heating of components and braze joints are coveredby the prior art and for this reason are not explained in more detail.

This is followed, as step b, by the mechanical cleaning of the brazepoints, which can be done, for example, by brushing or polishing. Inthis case, the exfoliated material and porous old braze are removed downto the bare copper or bare braze.

After this, in step c, the conductors of the end of the stator windingbar are aligned by heating the bar end to above the flow point of thebraze holding the conductors in position while simultaneously holdingthe conductors of the end of the stator winding bar under compression inthe two orthogonal directions perpendicular to the length of the statorwinding bar. The conductor elements 1 of the end of the stator windingbar, with the existing insulation stripped therefrom, are inserted intoan induction heating coil which may be of the type used in step a and ahydraulic press is positioned over the heating coil for pressing in thehorizontal and vertical directions. The braze holding the conductors inposition is then heated to above its flow point while the press appliespressure to align the conductors by closing the gaps therebetween.

After this--step d--the hydraulic press and heating coil are removed andthe end surface of the conductor bar is machined by metal-cuttingmachining, preferably by milling, until a clean copper surface isachieved.

In step e, narrow slots 7 having a width b≈0.5 mm and a depth t≈10-15 mmare introduced into the former braze gaps between mutually adjacentconductor elements 1, as is illustrated in FIGS. 3 and 4. This can bedone using a side-milling cutter which is mounted on an auxiliary deviceat the bar end. The essential feature in this case is that the width bof the slots is dimensioned such that the outer wall of the hollowconductor elements is also included in the milling process, so that theside wall of the slot 7 is machined, except for the conductor copper, asfar as the crossing points 8 where four conductor elements abut-againstone another.

In step f, one half 2a of a metallic connecting part is now pushed ontothe bar end which has been prepared in this manner. This half may bemanufactured from solid, rolled copper, or is forged, and is brought tothe corresponding shape by metal-cutting machining; it is thus not acasting. The dimensions of the hole in this first half at the end of thebar side largely correspond to the original bar end. It overhangs thebar end by a certain amount s. Taking into account the subsequentfitting of the second connecting part 2b, the excess amount should beselected to be as large as possible, as will be explained later inconjunction with FIG. 10.

Gaps which possibly still remain between the inner wall of the firstconnecting part 2a and all the outer surfaces of the conductor bar arenow (step g) filled with first filling strips 9. These first fillingstrips 9 have become known under the designation SILFOS and are offeredin a wide range of compositions and thicknesses which may be between 0.1mm and 1.2 mm. If required, copper-foil strips can also additionally beused in order to fill relatively large gaps as completely as possible aswell.

The slots 7 are now filled with second filling strips 10 (in step h).Since the slot width b (to be filled) is now produced by the millingtool and is thus defined, filling strips 10 are preferably consideredhere which comprise a central copper layer 11 with braze layers 12, 13arranged on both sides, as can be seen from the detailed illustration inFIG. 6. This results in the braze gaps being kept as small as possible,so that all the gaps are filled during the subsequent brazing step i, asa result of the capillary effect.

The bar end prepared in this way with the first connecting part 2apushed on is now inductively heated and brazed with the addition ofbraze (step i) to secure the first connecting part to the bar end.

There is also a concern that the aligned conductors at the end of thebar will lose their alignment during brazing step i. This possibility isminimized according to a feature of the invention illustrated in FIGS.12A, 12B and 13. Here, step f is performed by inserting the conductorelements 1 of the end of the stator winding bar into a modified firstconnecting part 2aa having a window 2ab at one lateral wall thereof. Awindow plate 2ac, which has a thickness greater than that of the firstconnecting part 2aa, is fitted in the window 2ab through theintermediary of a braze strip 2ad. Prior to the heating of step i,pressure is applied to window plate 2ac in the arrow direction, forexample via a conventional hydraulic press 102, which may be of the sametype used in step c. The pressure retains the aligned positions of theconductor ends during the subsequent brazing (step i) by inductionheating coil 100. A water jacket 104 having a cooling water flowcontrolled by the temperature sensed by the thermocouple 106 may be usedto protect the remaining insulation on the conductors. Upon thesolidification of the braze after step i, the bar end is unified withthe part 2aa, the alignment of the conductor ends is maintained, and thewindow plate 2ac is unified with the first connecting part 2aa by thebraze strip 2ad.

After the brazing of the first connecting part 2a, all the braze pointsare now inspected and investigated for freedom from porosity (in stepj). A sealing test can optionally be carried out even at this stage, forexample by provisional closure of the first connecting part and pressingoff, for example using helium gas, for example from the other side ofthe machine.

After completion of the inspection and, if appropriate, after reworkingof the braze points, the second connecting part 2b is now placed ontothe first connecting part 2a (in step k), with the interposition ofbraze foils (not shown in FIG. 5), and is brazed thereto. Like thefirst, this second part is also manufactured from solid copper and isbrought to the appropriate shape by metal-cutting machining; it is thusnot a casting. For reasons of completeness, it should be mentioned atthis point that the electrical connection is made to the secondconnecting part 2b in the case of this and all further variants, and thesecond connecting part 2b has been prepared with the first, even beforethe brazing. In order to enlarge those end surfaces of both connectingparts 2a, 2b which are to be brazed to one another, and in order tosimplify the mutual adjustment, these connecting parts 2a, 2b arestepped on their end surfaces. The silver braze which is used for thisjoint may in this case have a lower melting temperature than that usedfor brazing the first connecting part 2a to the bar end, in order toprevent damage to those silver-braze joints. Silver brazes having anincreased silver content are used in this case.

Completion of all the braze joints is followed by final inspectionaccording to step 1, in which the test for sealing by pressing offusing, for example, helium gas, is carried out as well as visualinspection.

In addition to the repair method which has been described in thepreceding text and is at the moment regarded as being preferred by theapplicant, modifications are possible without departing from theframework covered by the invention. One of these modifications relatesin particular to method step h. It is shown, by way of example, in FIGS.7 to 9.

After the first connecting part 2a has been pushed on in step f, and anyremaining gaps between this connecting part 2a and the outer surfaces ofthe bar end have been filled, "conventional" braze foil strips with athickness of approximately 1 mm are inserted into the slots 7. Thehollow conductor elements 1 are then widened at their end until theslots 7 which have been milled in step 4 are closed at the end (cf. FIG.7 in which the slots which are illustrated excessively wide are alreadyfilled with silver braze). The remaining critical gaps 8 at the pointwhere four adjacent conductors meet, which gaps 8 cannot be closed bythis widening, are now drilled down to a depth which may beapproximately 13 to 15 mm. It has in this case been found that it issufficient to accomplish this using a drill of 1 to 1. 5 mm. Pins 14,which are 13 to 15 mm long and are made of copper round material, arenow inserted into these holes (cf. FIGS. 8 and 9), and the gaps are inthis way closed. The purpose of this procedure is virtually to close allthe gaps in order to create capillaries for the liquid braze into whichit can flow and can also remain therein. Steps i to 1 then follow in theindicated manner.

As already mentioned, two brazing processes which are successive both intime and in space, must be carried out in the case of the repair methodaccording to the invention. In the case of such a process, there isalways the risk of the quality of the preceding brazing being adverselyaffected during a subsequent brazing process. In the present case, thisrisk can be avoided on the one hand by suitable selection of the meltingpoint of the silver braze. Another possibility is to design theconnecting device, more precisely the position of the separatingsurfaces of the two connecting parts 2a and 2b, such that the secondbraze point is as far as possible away from the first, that is to say toenlarge the distance s (cf FIGS. 5 and 7). However, this is dependent onthe structural characteristics at the site of the repair. In the case ofconnecting devices having a comparatively large extent, as isillustrated schematically in FIG. 10, the separating surface T of thetwo connecting parts 2a and 2b can be located a very long distance awayfrom the end surface of the conductor bar and towards the connectingfitting 5. However, nothing is changed in the described repair method,at most with the exception that one and the same braze can now be usedfor beth silver-brazing operations.

The repair method according to the invention has been described in thepreceding text with reference to a conductor bar consisting only ofhollow conductor elements 1. It is self-evident that the method is alsosuitable for stator winding bars which also have solid conductorelements 15 as well as hollow conductor elements 1 (cf. FIG. 11). In thecase of such an arrangement, and following the teaching of theinvention, after removal of the original connecting device, cleaning ofthe outer surfaces of the bar end, aligning the conductor ends andmilling its end flat, narrow slots are introduced between all theconductor elements 1, 15, that is to say also between adjacent hollowand solid conductor elements as well as between two adjacent solidconductor elements 15. The alternative (filling the slots only-withbraze foil and widening the hollow conductor elements 1 indicated instep h is admittedly possible here, but depends on the distribution ofthe hollow conductor elements in the conductor bar itself.

The essential feature in all the design variants of the invention is toensure in each case that all the earlier braze points are machined downto a predetermined depth seen from the bar end, and can thus be wettedwell by the "new" braze, and that all gaps which are too large for thebrazing are avoided or filled (capillary brazing).

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. A method of repairing a joint between conductorelements of a stator winding bar of an electrical machine and aconnecting device connected to an end of the stator winding bar forproviding electrical connection and coolant flow for the conductorelements, the method comprising the steps of:removing an existingconnecting device from the end of the stator winding bar; aligning theconductors of the end of the stator winding bar by heating the bar endto above the flow point of the braze holding the conductors in positionwhile simultaneously holding the conductors of the end of the statorwinding bar under compression in two orthogonal directions perpendicularto the length of the stator winding bar; forming slots in the end of thestator winding bar and at locations such that said slots extend tolocations where said conductor elements abut one another; applying anelectrically conductive first connecting part onto the end of the statorwinding bar such that said first connecting part substantially surroundssaid end of the stator winding bar; and sealing said slots and any gapsbetween the end of the stator winding bar and said electricallyconductive first connecting part.
 2. The method of claim 1 wherein saidsealing step comprises:filling gaps between said first connecting partand an outer surface of said end of the stator winding bar with at leastone first filler element; filling said slots with at least one secondfiller element; and heating at least one of said end of the statorwinding bar and said first connecting part, wherein at least one of saidfirst and second filler elements comprise at least one layer of amaterial which melts during said heating step, and adding sufficientadditional meltable material to assure complete sealing of said gaps andslots.
 3. The method of claim 1 wherein said sealing stepcomprises:filling gaps between said first connecting part and an outersurface of said end of the stator winding bar with at least one firstfiller element; filling said slots with at least one second fillerelement; and inductive heating at least one of said end of the statorwinding bar and said first connecting part, wherein at least one of saidfirst and second filler elements comprise at least one layer of amaterial which melts during said heating step, and adding sufficientadditional meltable material to assure complete sealing of said gaps andslots.
 4. The method of claim 3 including the further steps of:visuallyinspecting said sealed gaps via said first connecting part; and applyingan electrically conductive second connecting part onto said firstconnecting part so as to form a complete connecting part.
 5. The methodof claims 1 including a step of cleaning said end of the stator windingbar after the step of removing the existing connecting device.
 6. Themethod of claims 1 including a step of material-cutting machining saidend of the stator winding bar after the step of removing the existingconnecting device.
 7. The method of claim 6 wherein saidmaterial-cutting machining comprises milling.
 8. The method of claims 1wherein at least one of said conductor elements is hollow.
 9. The methodof claims 1 wherein at least one of said conductor elements is solid.10. The method of claims 1 wherein said step of removing an existingconnecting device from the end of the stator winding bar comprisesinductive heating at least one of said stator winding bar and saidconnecting device.
 11. The method of claim 1 wherein groups of four ofsaid conductor elements abut one another at points and said slots extendto said points.
 12. The method of claim 10 wherein said slots formstraight lines.
 13. The method of claim 10 wherein said slots formintersecting sets of straight lines which intersect at said points. 14.The method of one of claims 2 wherein at least one of said first andsecond filler elements comprise a spacer element.
 15. The method of oneof claims 3 wherein at least one of said first and second fillerelements comprise a spacer element.
 16. The method of claim 8 including,after said slot forming step, the step of widening said hollow conductorelements at said end of the stator winding bar until edges of adjacentconductor elements touch one another.
 17. The method of claim 16 whereingroups of four of said conductor elements abut one another at points andsaid slots extend to said points, including the step of drilling holesinto said bar at said points and inserting pins of meltable materialinto the drilled holes.
 18. A method of repairing a joint betweenconductor elements of a stator winding bar of an electrical machine anda connecting device connected to an end of the stator winding bar forproviding electrical connection and coolant flow for the conductorelements, the method comprising the steps of:removing an existingconnecting device from the end of the stator winding bar; aligning theconductors of the end of the stator winding bar by heating the bar endto above the flow point of the braze holding the conductors in positionwhile simultaneously holding the conductors of the end of the statorwinding bar under compression in two orthogonal directions perpendicularto the length of the stator winding bar; applying an electricallyconductive first connecting part onto the end of the stator winding barsuch that said first connecting part substantially surrounds said end ofthe stator winding bar; and sealing any gaps between the end of thestator winding bar and said electrically conductive first connectingpart.
 19. The method of claim 18 including the step of maintaining thealignment of the conductors of the end of the stator winding bar duringsaid sealing step.
 20. The method of claim 19 wherein said maintainingstep comprises:applying, in said applying step, an electricallyconductive first connecting part having a window covered by a floatingcover plate; filling gaps between said first connecting part and anouter surface of said end of the stator winding bar with at least onebraze filler element; applying pressure to the conductors of the end ofthe stator winding bar via said floating cover plate; and heating, insaid sealing step, at least one of said end of the stator winding barand said first connecting part to melt said at least one braze fillerelement, while maintaining said pressure.
 21. A method of repairing ajoint between conductor elements of a stator winding bar of anelectrical machine and a connecting device connected to an end of thestator winding bar for providing electrical connection and coolant flowfor the conductor elements, the method comprising the steps of:removingan existing connecting device from the end of the stator winding bar;cleaning said end of the stator winding bar; aligning the conductors ofthe end of the stator winding bar by heating the bar end to above theflow point of the braze holding the conductors in position whilesimultaneously holding the conductors of the end of the stator windingbar under compression in the two orthogonal directions perpendicular tothe length of the stator winding bar; material-cutting machining saidend of the stator winding bar; forming slots in the end of the statorwinding bar and at locations such that said slots extend to locationswhere said conductor elements abut one another; applying an electricallyconductive first connecting part onto the end of the stator winding barsuch that said first connecting part substantially surrounds said end ofthe stator winding bar; filling gaps between said first connecting partand an outer surface of said end of the stator winding bar with at leastone first filler element; filling said slots with at least one secondfiller element; sealing said gaps and slots by heating at least one ofsaid end of the stator winding bar and said first connecting part, atleast one of said first and second filler elements comprising at leastone layer of a material which melts during said heating step, and addingsufficient additional meltable material to assure complete sealing ofsaid gaps and slots; visually inspecting said sealed gaps via said firstconnecting part; applying an electrically conductive second connectingpart onto said first connecting part so as to form a complete connectingpart; and testing the repaired joint.
 22. The method of claim 18including the step of maintaining the alignment of the conductors of theend of the stator winding bar during said sealing step.
 23. The methodof claim 19 wherein said maintaining step comprises:applying, in saidstep of applying an electrically conductive first connecting part ontothe end of the stator winding bar, an electrically conductive firstconnecting part having a window covered by a floating cover plate;applying pressure to the conductors of the end of the stator winding barvia said floating cover plate; and heating, in said sealing step, atleast one of said end of the stator winding bar and said firstconnecting part to melt said at least one first filler element, whilemaintaining said pressure.